This is a double-blind random assignment study in which patients diagnosed as schizoaffective by the Research Diagnostic Criteria will be randomly assigned to either lithium or fluphenazine (Prolixin). Eligible patients must have had 1) at least one schizoaffective episode or 2) at least one major affective episode and one schizophrenic episode. This is a prophylaxis study so all patients must be clinically stable on both active lithium and active fluphenazine for at least six weeks before random assignment occurs. Patients will be evaluated in terms of symptomatology, premorbid history, previous response to medication, family history, and role of psychogenic precipitants in inducing relapse, to attempt to identify predictors of differential benefit with the two medications.